gis4dis / cg

Cartographic generalization

cg

Cartographic generalization

Requirements

• Node.js 9+

Installation

git clone https://github.com/gis4dis/cg.git
cd cg
npm install

Run

OpenLayers in the browser

npm run dev
# open localhost:3000
```bash

### OpenLayers in Node.JS
```bash
node task/ol-node.js

Run Jasmine Specs

node spec/run

Repository Structure

/build          NextJS build directory
/components     NextJS components
/data           any data for testing
/pages          NextJS pages
/src            gis4dis CG subsystem (ES6 modules should be used)
/static         NextJS static content
/task           Node.JS commands (ES6 modules should not be used)

cg's Issues

Implement first version of generalize method

Implement first version of generalize method.

The first version will only assign styles to the features (no generalization needed).

Features included inside aggregated features

Every aggregated feature will have parameter containing all features aggregated inside one bigger feature.

Repair centering of symbols

Missing dependency

This dependency was not found:

• @turf/polygon-smooth in ./node_modules/gis4dis-generalizer/src/cg/helpers.js

To install it, you can run: npm install --save @turf/polygon-smooth

Please check the dependency in your package.json.

Prepare cg as installable npm package

In package.json set appropriate name, version, and main (should point to file with generalize method). @kordilery can then use your app as package.

Image is not defined

Error during the caching (branch imageerror):

Image is not defined

ReferenceError: Image is not defined
    at new Image (/home/bulva/WebstormProjects/cg/node_modules/ol/style/iconimage.js:34:30)
    at Function.module.exports../node_modules/ol/style/iconimage.js._ol_style_IconImage_.get (/home/bulva/WebstormProjects/cg/node_modules/ol/style/iconimage.js:106:17)
    at new get (/home/bulva/WebstormProjects/cg/node_modules/ol/style/icon.js:108:42)
    at Symbolizer.buildStyle (/home/bulva/WebstormProjects/cg/build/dist/bundles/pages/index.js:46715:24)
    at Symbolizer.styleBasedOnProperty (/home/bulva/WebstormProjects/cg/src/cg/symbolizers/Symbolizer.js:166:13)
    at styleBasedOnProperty (/home/bulva/WebstormProjects/cg/src/cg/generalize.js:101:53)
    at Array.forEach (<anonymous>)
    at forEach (/home/bulva/WebstormProjects/cg/src/cg/generalize.js:88:24)
    at Array.forEach (<anonymous>)
    at forEach (/home/bulva/WebstormProjects/cg/src/cg/generalize.js:82:27)
    at Object.generalize (/home/bulva/WebstormProjects/cg/component/Map.js:13:28)
    at __webpack_require__ (/home/bulva/WebstormProjects/cg/build/dist/bundles/pages/webpack/bootstrap 436ba26c890e5ef3d3bb:21:1)
    at Object../pages/index.js (/home/bulva/WebstormProjects/cg/build/dist/bundles/pages/index.js:46075:73)
    at __webpack_require__ (/home/bulva/WebstormProjects/cg/build/dist/bundles/pages/webpack/bootstrap 436ba26c890e5ef3d3bb:21:1)
    at Object.2 (/home/bulva/WebstormProjects/cg/build/dist/bundles/pages/index.js:46833:18)
    at __webpack_require__ (/home/bulva/WebstormProjects/cg/build/dist/bundles/pages/webpack/bootstrap 436ba26c890e5ef3d3bb:21:1)

It's terribly slow

About 4 second per frame when click to play (e.g. 2019-05-06). Not sure when this problem appeared, but it wasn't so slow before (it used to be definitely under 1 second). I guess it's related to aggregation/interpolation.

NaN value in CombinedSymbol setBuffer method

In CombinedSymbol, NaN value appears in maxValue variable if feature's array of values is shorter than the length given by date range - value_idx can overflow values lenght:
https://github.com/gis4dis/cg/blob/master/src/cg/symbolizers/CombinedSymbol.js#L139

And it looks like at least in this case value_index_shift is not taken into account, please check the documentation:
https://github.com/gis4dis/poster/wiki/Interface-between-MC-client-&-CG-v2#parameters

Width of columns is too big (based on resolution)

Width of columns is too big when user zoom out and resolution of view is to big. It is necessary to modify a formula for computing width of columns.

Generalization tasks

Generalization

1. Concave envelope (1027ce3)
2. Distance between points - find a middle of the cluster and replace by the point (partially d27a3ed)
3. Density of points - size of the circle and number of the points inside the circle
4. BFR (Best Fit Rectangle) - ellipse from the rectangle (find orientation). Concave or ellipse?

Testing between layers

1. Intersections between layers (inside or cross)
2. Compute value of intersection

Symbols are not aggregating when changing zoom level

Saving style in feature (combinedSymbol) does not work for MC-client

Features in a layer source are updated based on id - see code
In a newer version, CG stores combinedSymbol to derive current style directly in the feature. As features are not updated in layer source, style is NOT updated as well.

Symbolizer.normalize fails if value === min && max === min

In normalize function, if value === min && max === min, the first part of expression is evaluated as 0 / 0 and the function returns NaN.

Inconsistency in rightmost processing

How to reproduce it:

• https://gis4dis-poster-master.g4d.sci.muni.cz/topics/drought/
• select date from 2019-05-19 to 2019-05-19
• click Play

Implementation of clustering

Implement clustering of points based on line shapes and polygons shapes. Should be used turf.js including direction of the points (and the cluster).

Implementation of style caching

Style are flickering, style caching need to be implemented.

Change symbolization

Change symbolization for anomaly rates. Color will be better for rates.

Green and yellow colors switched?

See this animation
https://drive.google.com/file/d/1ywANVWbpjA8AXwrGGL1tpgvgrlPi1OWQ/view?usp=sharing
The red line in chart shows anomaly rate. Colors of map symbols (thermometers in this case) should reflect this anomaly rate in order green < yellow < red. However it seems like the order is now yellow < green < red, that is quite strange.

Note: symbol with popup is currently not animated, as describe in another issue.

Style caching involving property

Extend style cache hash derivation by primary property name_id.